The performance of Li-ion batteries degrades during cycling and under storage conditions due to cell capacity loss and resistance rise. Several cell aging mechanisms have been identified to be responsible for this performance decay. Solid Electrolyte Interphase (SEI) formation on anode particles, SEI film growth, metallic Li plating side reaction in anode, particle cracking, contact loss of active material particles, and electrode porosity reduction are the main degradation mechanisms in typical Li-ion cells. Capacity fade mechanisms can be categorized into three main groups: loss of cyclable Lithium ion, loss of anode active material, and loss of cathode active material. For instance, SEI formation and Li plating contribute primarily to loss of cyclable Lithium while the particle cracking is mostly responsible for loss of electrodes' active materials. Existing state of health estimation methods do not predict the state of each electrode and the amount of available lithium in a battery cell, and as a result to not provide adequate information to identify degradation issues in a battery cell.